• Journal of Chest Surgery
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• v.44 no.6
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• pp.399-405
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• 2011

Background: Left ventricular (LV) hypertrophy caused by aortic valve stenosis (AS) leads to cardiovascular morbidity and mortality. We sought to determine whether aortic valve replacement (AVR) decreases LV mass and improves LV function. Materials and Methods: Retrospective review for 358 consecutive patients, who underwent aortic valve replacement for degenerative AS between January 1995 and December 2008, was performed. There were 230 men and 128 women, and their age at operation was $63.2{\pm}10$ years (30~85 years). Results: There was no in-hospital mortality, and mean follow-up duration after discharge was 48.9 months (2~167 months). Immediate postoperative echocardiography revealed that LV mass index and mean gradient across the aortic valve decreased significantly (p<0.001), and LV mass continued to decrease during the follow-up period (p<0.001). LV ejection fraction (EF) temporarily decreased postoperatively (p<0.001), but LV function recovered immediately and continued to improve with a significant difference between preoperative and postoperative EF (p<0.001). There were 15 late deaths during the follow-up period, and overall survival at 5 and 10 years were 94% and 90%, respectively. On multivariable analysis, age at operation (p=0.008), concomitant coronary bypass surgery (p<0.003), lower preoperative LVEF (<40%) (p=0.0018), and higher EUROScore (>7) (p=0.045) were risk factors for late death. Conclusion: After AVR for degenerative AS, reduction of left ventricular mass and improvement of left ventricular function continue late after operation.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.22
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• pp.10027-10031
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• 2014

Background: We investigated the risk of cancer mortality according to obesity status and metabolic health status using sampled cohort data from the National Health Insurance system. Materials and Methods: Data on body mass index and fasting blood glucose in the sampled cohort database (n=363,881) were used to estimate risk of cancer mortality. Data were analyzed using a Cox proportional hazard model (Model 1 was adjusted for age, sex, systolic blood pressure, diastolic blood pressure, total cholesterol level and urinary protein; Model 2 was adjusted for Model 1 plus smoking status, alcohol intake and physical activity). Results: According to the obesity status, the mean hazard ratios were 0.82 [95% confidence interval (CI), 0.75-0.89] and 0.79 (95% CI, 0.72-0.85) for the overweight and obese groups, respectively, compared with the normal weight group. According to the metabolic health status, the mean hazard ratio was 1.26 (95% CI, 1.14-1.40) for the metabolically unhealthy group compared with the metabolically healthy group. The interaction between obesity status and metabolic health status on the risk of cancer mortality was not statistically significant (p=0.31). Conclusions: We found that the risk of cancer mortality decreased according to the obesity status and increased according to the metabolic health status. Given the rise in the rate of metabolic dysfunction, the mortality from cancer is also likely to rise. Treatment strategies targeting metabolic dysfunction may lead to reductions in the risk of death from cancer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.4
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• pp.407-418
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• 2020

Mass mortality of mariculture fish due to high summer temperatures is a major issue in the mariculture industry in many coastal waters of Korea, yet measures to mitigate the impact are generally limited. We injected a micro-bubble of liquefied oxygen into the bottom of rockfish cages (about 6-8 m deep) in order to maximize the dispersal of micro-bubbled seawater and reduce fish mortality. The injection of low-temperature oxygen in micro-bubbles lowered the water temperature at the injection area by as much as 1℃ and increased dissolved oxygen concentration by 0.5 ppm. In early August, following a week with persistent high water temperature (above 28.5℃), there was an increase in fish mortality despite the micro-bubble system, which resulted in approximately 7% death of the total introduced fish population. However, this mortality appeared to be much lower than mortality reported in a neighboring mariculture facility (approximately 50% mortality). We also estimated the volume that can be recirculated with pumped seawater using a micro-bubble system. We suggest that this approach of injecting liquefied oxygen through a micro-bubble system may reduce fish mortality during high temperature periods.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3105-3108
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• 2013

Background: This study used National Health and Nutrition Examination Survey III to study the relationship between blood lead concentration and all cause, all cancer and lung cancer mortality in adults. Patients and Methods: Public use National Health and Nutrition Examination Survey (NHANES III) data were used. NHANES III uses stratified, multistage probabilistic methods to sample nationally representative samples. Household adult, laboratory and mortality data were merged. Sample persons who were available to be examined in aMobile Examination Center (MEC) were included in this study. Specialized survey analysis software was used. Results: A total of 3,482 sample participants with complete information for all variables were included in this analysis. For all cause death, the odds ratios (S.E.) for statistically significant variables were body mass index, 1.03 (1.01-1.06); 1.01 (1.01-1.01); blood lead concentration, 1.05 (1.01-1.08); poverty income ratio, 0.823 (0.76-0.89); and drinking hard liquor, 1.01 (1.00-1.02). For all cancer mortality, the odds ratios (S.E.) of the statistically signigicant variables were: age, 1.01 (1.01-1.01); blood lead concentration, 1.07 (1.04-1.12), black race, using non-Hispanic white as reference, 1.69 (1.12-2.56); and smoking, 1.02 (1.01-1.04). For lung cancer mortality, the odds ratios (S.E.) of the statistically significant variables were: age, 1.01(1.01-1.01); blood lead concentration, 1.09 (1.05-1.13); Mexican Americans, using non-Hispanic white as refrence, 0.33 (0.129-0.850); other races, 1.80 (0.53-6.18); and smoking, 1.03 (1.02-1.05). Conclusion: Blood lead concentration correlated with all cause, all cancer, and lung cancer mortality in adults.

• Journal of Preventive Medicine and Public Health
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• v.45 no.1
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• pp.14-20
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• 2012

Objectives: The aim of this study was to evaluate and quantify the risk of both individual and combined health behaviors on premature mortality in middle aged men in Korea. Methods: In total, 14 533 male subjects 40 to 59 years of age were recruited. At enrollment, subjects completed a baseline questionnaire, which included information about socio-demographic factors, past medical history, and life style. During the follow-up period from 1993 to 2008, we identified 990 all-cause premature deaths using national death certificates. A Cox proportional hazard regression model was used to estimate the hazard ratio (HR) of each health risk behavior, which included smoking, drinking, physical inactivity, and lack of sleep hours. Using the Cox model, each health behavior was assigned a risk score proportional to its regression coefficient value. Health risk scores were calculated for each patient and the HR of all-cause premature mortality was calculated according to risk score. Results: Current smoking and drinking, high body mass index, less sleep hours, and less education were significantly associated with all-cause premature mortality, while regular exercise was associated with a reduced risk. When combined by health risk score, there was a strong trend for increased mortality risk with increased score (p-trend < 0.01). When compared with the 1-9 score group, HRs of the 10-19 and 20-28 score groups were 2.58 (95% confidence intervals [CIs], 2.19 to 3.03) and 7.09 (95% CIs, 5.21 to 9.66), respectively. Conclusions: Modifiable risk factors, such as smoking, drinking, and regular exercise, have considerable impact on premature mortality and should be assessed in combination.

• Journal of Preventive Medicine and Public Health
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• v.56 no.5
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• pp.458-466
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• 2023

Objectives: The association between long sleep duration and mortality is frequently attributed to the confounding influence of comorbidities. Nevertheless, past efforts to account for comorbidities have yielded inconsistent outcomes. The objective of this study was to evaluate this relationship using a large prospective cohort in Korea. Methods: The study included 114 205 participants from the Health Examinees Study, who were followed for a median of 9.1 years. A composite comorbidity score was developed to summarize the effects of 21 diseases. Using Cox proportional hazards regression, hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause, cancer, and cardiovascular mortality associated with sleep duration were estimated. These estimates were adjusted for socio-demographic factors, lifestyle factors, body mass index, and comorbidity score. Additionally, a stratified analysis by subgroups with and without comorbidities was conducted. Results: Throughout the follow-up period, 2675 deaths were recorded. After all adjustments, an association was observed between a sleep duration of 8 hours or more and all-cause mortality (HR, 1.10; 95% CI, 1.01 to 1.20). However, no such association was detected in the stratified analysis for the subgroups based on comorbidity status. Conclusions: Long sleep duration was found to be associated with all-cause mortality among Koreans, even after adjusting for comorbidities. Additional studies are required to explore the mechanism underlying the association between sleep duration and major causes of mortality.

• Korean Circulation Journal
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• v.53 no.10
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• pp.710-719
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• 2023

Background and Objectives: In previous studies, high homocysteine levels were associated with high cardiovascular mortality. However, these results were inconsistent with those of randomized controlled trials. We aimed to evaluate the causal role of homocysteine on allcause and cardiovascular mortality using Mendelian randomization (MR) analysis. Methods: This study included the 10,005 participants in the Namwon Study. In conventional observational analysis, age, sex, survey years, lifestyles, body mass index, comorbidities, and serum folate level were adjusted using multivariate Cox proportional regression. MR using 2-stage least squares regression was used to evaluate the association between genetically predicted plasma homocysteine levels and mortality. Age, sex, and survey years were adjusted for each stage. The methylenetetrahydrofolate reductase (MTHFR) polymorphism was used as an instrumental variable for predicting plasma homocysteine levels. Results: Observed homocysteine levels were positively associated with all-cause (hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.26-1.54) and cardiovascular (HR, 1.62; 95% CI, 1.28-2.06) mortality when plasma homocysteine levels doubled. However, these associations were not significant in MR analysis. The HRs of doubling genetically predicted plasma homocysteine levels for all-cause and cardiovascular mortality were 0.99 (95% CI, 0.62-1.57) and 1.76 (95% CI, 0.54-5.77), respectively. Conclusions: This MR analysis did not support a causal role for elevated plasma homocysteine concentrations in premature deaths.

• The Korean Journal of Malacology
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• v.15 no.1
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• pp.49-55
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• 1999

Mass mortality of the horned turban shell, Batillus cornutus was investigated using histological and bacteriological methods. Some pathogenic bacteria were isolated from mortal or inactive individuals. The pathogenic agents causing mortality of the horned turban shells were as Vibrio alginolyticus and V. anguillarum. Laboratory experiment indicated that optimal growth temperature of two bacteria was 25 to 30$^{\circ}C$ and 3% of NaCl. Histological examination of the horned turban shells showed that gill necrosis is one of the major symptom of infected individuals. It was believed that sudden increase of those two bacterial agents due to environmental change cause mortality of horned turban shells.

• Journal of fish pathology
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• v.16 no.2
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• pp.135-138
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• 2003

The research was carried out to know the occurrence trend of scuticociliatosis and mortality of fingerlings in flounder. The diseased fish were collected from on-land rearing farms lind hatcheries of flounder in Jeju Island from January 1991 to December 2001. Occurrence of scuticociliatosis was about 10% of total occurred diseases from 1991 to 1996, but increased to 34.5% in 2001. Although monthly occurrence of scuticociliatosis was not related to season from 1999 to 2001, the highest occurrence was revealed in July and August. Mixed infections of bacteria including Vibrio sp. Edwardsiella tarda, Streptococcus sp., and Flexibacter sp. with scuticociliates were observed. Among the bacteria, Vibrio sp. was the highest frequency(40.1%), and the lowest one(10.1%) was Streptococcus sp., Mortality of fingerlings by scuticociliates was different sharply according to size of fish. Mortality of infected fingerlings below 7 cm of total length was 53.8%, while that of normal fingerling above 7 cm of total length was 13.2%. When fish were grown above 25 cm, mass mortality by scuticociliates infection was decreased markedly.

• Journal of Preventive Medicine and Public Health
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• v.46 no.4
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• pp.155-164
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• 2013

Noncommunicable diseases (NCDs) are the most important causes of premature mortality and disability-adjusted life years in Korea. NCDs are also the main contributor to socioeconomic inequalities in mortality and life expectancy. Reduction of NCDs and NCD inequalities would result in significant improvement in healthy life expectancy and health equity in Korea. Major NCD risk factors such as dietary risks (including salt intake), alcohol consumption, cigarette smoking, and high blood pressure were found to be the leading modifiable risk factors of disability-adjusted life years in Korea, based on the 2010 Global Burden of Disease Study. Several Korean studies have shown that these risk factors play an important role in creating socioeconomic inequalities in NCD mortality and total mortality. Current international discussions on NCD policies in the United Nations and the World Health Organization would provide better opportunities for developing aggressive population-wide policy measures in Korea. Considering the paucity of population-wide policies to control major NCD risk factors in Korea, rigorous population approaches such as taxation and regulation of unhealthy commodities as well as public education and mass campaigns should be further developed in Korea.